Intraocular lenses (IOL) are typically implanted during cataract surgery where the natural lens is replaced with an IOL. Currently the majority of commercially available IOLs are either circular shaped or plate shaped with an embedded circular optic body in the middle of the plate. Both shapes result in clinically observed light artifacts, generically called dysphotopsia, which may be bothersome to the person with the implanted IOL.
There are two types of dysphotopsia: positive dysphotopsia (PD) and negative dysphotopsia (ND). PD defines unexpected “bright” images such as arcs or rings while ND refers to unexpected “dark” images such as shadows or lines. While PD is determined by light reflected by the edge of the IOL, ND arises from both light refracted by the edge of the IOL as well as light that passes through the eye without encountering the IOL.
Due to the bothersome nature of PD and ND, it would be beneficial if the amount of PD and ND resulting from a particular IOL design could be measured. IOL design modifications could then be made in order to reduce or eliminate PD and/or ND. Currently, in either laboratory or clinic environments, there are no metrics for the objective measurement of PD or ND.
For these and other reasons there is a continuous need for the development of improved devices and techniques aiming to qualitatively and quantitatively measure PD and ND.